Circuit density

Additive and semiadditive processing can give material savings and higher circuit densities, whereas subtractive processing is technologically easier. 

Polymer chemistry and polymer radiation chemistry in particular are key elements of the electronics industry. Polymer materials that undergo radiation induced changes in solubility are used to define the individual elements of integrated circuits. As the demands placed on these materials increases due to increased circuit density and complexity, new materials and chemistry will be required. Many of the new chemistries that are being developed are described in this article. 

Recently, photovoltaic cells that use a narrow band conjugated polymer PDDTT 196 as the electron donor and fullerene derivative 197 as the electron acceptor were developed. These cells show a short circuit density (J c) of 0.83mAcm , an open current voltage (Fqc) of 0.35 V, a fill factor (FF) of 38.6% under AM.5 simulator (lOOmWcm ) and unprecedented photocurrent response wavelengths up to llOOnm <2006APY081106>. 

Heat Dissipation. The very high power densities resulting from increased circuit density and speed require innovative approaches for dissipating heat, such as heat pipes (160, 161), immersion cooling (64-66), or structures such as microchannels (162, 163) or microcapillaries (163-165) etched into the substrate or fabricated internally within a cofired ceramic substrate (166). 

Wafer-Scale Integration. One of the most well-publicized and widely debated approaches to increase system performance is wafer-scale integration (WSI), in which an entire system or a large functional block of circuits is integrated on a large chip approaching the size of a silicon wafer (168-171). WSI can greatly increase circuit density, improve reliability because of fewer interconnections, and increase speed and reduce power be-... 

This increase in circuit density is made possible only by decreasing the minimum feature size on the chip. Figure 2 illustrates the decrease in minimum feature size as a function of time for dynamic random access memory (DRAM) devices. In 1975, the 4-kilobit DRAM (4 X 10 memory cells or about 8.2 X 10 transistors) had features in the 7-9-(xm range, and by 1987,... 

NTEGRATED CIRCUIT (IC) TECHNOLOGY has moved Steadily toward increasing circuit density and improved performance during its brief history. These improvements have been achieved through the development of the microlithography process, which now permits production of devices with feature sizes of 1 fim. Submicrometer devices are actively being developed, and production is expected later in this decade. 

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